Melting and Evaporating Sodium Tellurite Melts in Low-gravity Drop Shaft
Glasses of Na2 xTe2(x=2,4 and 6) compositions were remelted and evaporated while supported by a platinum heater coil in the low gravity (~10-5g) drop shaft at the Japan Microgravity Center (JAMIC). The evaporating species from all the melts, which formed a spherical cloud surrounding the melt during the few seconds low gravity time were identified to be amorphous particles of TeO2. These particles were highly spherical, 5 to 10 µm in diameter, and were, on the average, 6 to 8 times larger than the particles grown from similar experiments at 1-g. The melt remaining after evaporation was splattered on to a glass plate positioned at about 3.5 cm directly below the melt during the high-g (~8 to 10 g) deceleration of the drop capsule and crystallized almost instantaneously. The chemical composition of the crystallized splatters was same as that of the starting glass. The crystallization tendency of these sodium tellurite platters was estimated to be at least 1000 times greater than that of an identical melt at 1-g. No suitable explanation was found for the high crystallization tendency of the drop shaft splatters, but a sudden 5 orders of magnitude increase in the gravity level is suspected to be a contributing facto for this effect.
M. Makihara et al., "Melting and Evaporating Sodium Tellurite Melts in Low-gravity Drop Shaft," Proceedings of SPIE, SPIE -- The International Society for Optical Engineering, Jul 1999.
The definitive version is available at http://dx.doi.org/10.1117/12.351279
Materials Science and Engineering
Article - Conference proceedings
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